Commercial walk-in coolers, such as those commonly found in convenience stores and commercial food storage facilities such as supermarkets, are typically constructed of insulating wall, ceiling and floor panels that are fastened together. The panel ends are shaped to fit together in tongue and groove fashion and are provided with latch type fastening means for drawing and holding adjacent panels together. The latches themselves commonly comprise a hook and cam assembly inside a casing that is mounted to one panel for latching engagement with a pin assembly inside a casing that is mounted to an adjacent panel.
The hook and cam assembly includes a C-shaped leaf spring that operates in a clutch like action by transferring torque from the cam to the hook. The advantage of using a C-shaped cam spring is that it provides sufficiently high frictional resistance for driving the hook. To position the spring into the cam the hook is provided with a cam hole that is ob-round, meaning that it is not completely round but instead has a portion that is round and a spring recess extending from the round portion that creates a space, as shown in FIG. 4. During assembly, the cam is oriented so that the relaxed spring is coupled to the cam by inserting it into the spring recess.
During actuation of the latch, the cam turns bringing the spring into engagement with the hook and thereby compressing the spring. This causes the spring to shift in a direction opposite to the direction in which the hook is driven.
A problem which may occur with the ob-round hole design is that the cam can be rotated under certain circumstances to release the hook, which renders the fastener unable to be reset. If this occurs, manual intervention or replacement becomes necessary to correct the situation. The spring may also become dislodged if it is moved back to a position within the spring recess, due to the spring becoming de-compressed.
It thus is seen that a need has long existed for a panel fastener with a cam and hook assembly of the type that employs a C-shaped spring that is easier to manufacture and is not susceptible to the spring being disengaged. It is to the provision of such that the present invention is primarily directed.